Recently (2009) retired enlisted person here. If your dedicated to school you can enlist, go through tech school, and then get to your first base. Once you get to your first base you will have what is called CDC's to complete, Career Development Course. Pretty much every squadron will not let you take college courses till your CDC's are complete. You get 1 month per volume of CDC's, some jobs have 2 volumes, some have many more. Once you complete your CDC's go to the Base Education office and start taking classes (online or traditional) as you see fit. Tuition is 100% paid while you are in. You will have to pay for books, but there are always Pell Grants, loans, etc. If you dedicate yourself you can finish your Bachelors in 4yrs, even with deployments, but YOU HAVE TO DEDICATE YOURSELF TO IT. Far to often young folks enlist then decide that partying with their co-workers and getting hammered every weekend is the way to go. Once you get your degree you can apply for officer training. This would also allow you to save your GI Bill benefits for transfer to your wife/future wife or children if you so choose. Take it from me, or don't... I did not get my Bachelors in 4yrs, hell after 21 I only have my Assosciates, but I did have a lot of fun
You could join any service and become the highest ranking enlisted person, Chief Master Sergeant in the Air Force, and at 20yrs you would be making $5436.60 a month, or... you could go active duty, get your degree, become an officer, and by the time you are at 8yrs total service, and a captain (03E) you would be making $5449.20. After that pay goes up substantially. I tell all the young enlisted kids that I talk to that you could do 20+ as a Chief and have all the respect in the world, cause quite frankly most Chiefs are pretty awesome, or you could be an officer and at the end of the day, with the same amount of time in service be making a WHOLE lot more $$. Go to school. Get your degree.